scholarly journals The Length of Shortest Vertex Paths in Binary Occupancy Grids Compared to Shortest r-Constrained Ones

2017 ◽  
Vol 59 ◽  
pp. 543-563
Author(s):  
Patrick Chisan Hew
Keyword(s):  
Path Length ◽  
Upper Bounds ◽  
Line Of Sight ◽  
Brute Force ◽  
Line Segments ◽  
Cell Corner ◽  
Classic Approach ◽  
Occupancy Grids ◽  
A Cell ◽  
The Difference

We study the problem of finding a short path from a start to a goal within a two-dimensional continuous and isotropic terrain that has been discretized into an array of accessible and blocked cells. A classic approach obtains a grid path where each step is along the edge of an accessible cell or diagonally across one. Grid paths suffer from `digitization bias' -- even if two locations have line-of-sight, the minimum travelling cost between them can be greater than the distance along the line-of-sight. In a vertex path, steps are allowed from a cell corner to any other cell corner if they have line-of-sight. While the `digitization bias' is smaller, shortest vertex paths are impractical to find by brute force. Recent research has thus turned to methods for finding short (but not necessarily shortest) vertex paths. To establish the methods' potential utility, we calculate upper bounds on the difference in length between the shortest vertex paths versus the shortest r-constrained ones where an r-constrained path consists of line segments that each traverse at most r rows and at most r columns of cells. The difference in length reduces as r increases -- indeed the shortest vertex paths are at most 1 percent shorter than the shortest 4-constrained ones. This article will be useful to developers and users of short(est) vertex paths algorithms who want to trade path length for improved runtimes in a predictable manner.

Structuring, Motions and Shapes of Corona Emission Line Profiles

1994 ◽  
Vol 144 ◽  
pp. 421-426
Author(s):  
N. F. Tyagun
Keyword(s):  
Emission Line ◽  
Filling Factor ◽  
Direct Relationship ◽  
Coronal Plasma ◽  
Line Of Sight ◽  
Line Profiles ◽  
The Difference ◽  
Yellow Line ◽  
Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

Effect of Bilingualism on Multitasking: A Pilot Study

2015 ◽  
Vol 22 (3) ◽  
pp. 94-101 ◽  
Author(s):  
Li Hsieh
Keyword(s):  
Executive Control ◽  
Positive Impact ◽  
Reaction Times ◽  
Language Experience ◽  
Bilingual Advantage ◽  
Bilingual Speakers ◽  
Proficiency Level ◽  
Linguistic Representations ◽  
A Cell ◽  
The Difference

Bilingual speakers rely on attentional and executive control to continuously inhibit or activate linguistic representations of competing languages, which leads to an increased efficiency known as “bilingual advantage”. Both monolingual and bilingual speakers were asked to perform multiple tasks of talking on a cell phone while simultaneously attending to simulated driving events. This study examined the effect of bilingualism on participants' performance during a dual-task experiment based on 20 monolingual and 13 bilingual healthy adults. The within-subject and between-subject comparisons were conducted on reaction times of a visual event detection task for (a) only driving and (b) driving while simultaneously engaged in a phone conversation. Results of this study showed that bilingual speakers performed significantly faster than monolingual speakers during the multitasking condition, but not during the driving only condition. Further, bilingual speakers consistently showed a bilingual advantage in reaction times during the multitasking condition, despite varying degrees on a bilingual dominance scale. Overall, experiences in more than one language yield bilingual advantage in better performance than monolingual speakers during a multitasking condition, but not during a single task condition. Regardless of the difference in bilingual proficiency level, such language experience reveals a positive impact on bilingual speakers for multitasking.

scholarly journals Assessment of the Single-Mixture Gas Assumption for the Correlated K-Distribution Fictitious Gas Method in H2O–CO2–CO Mixture at High Temperature

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
C. Caliot ◽  
G. Flamant ◽  
M. El Hafi ◽  
Y. Le Maoult
Keyword(s):  
Remote Sensing ◽  
Path Length ◽  
Narrow Band ◽  
Specific Area ◽  
Sensitivity Study ◽  
Computational Time ◽  
Line Of Sight ◽  
Spectral Bands ◽  
Integrated Intensity ◽  
Atmospheric Path

This paper deals with the comparison of spectral narrow band models based on the correlated-K (CK) approach in the specific area of remote sensing of plume signatures. The CK models chosen may or may not include the fictitious gas (FG) idea and the single-mixture-gas assumption (SMG). The accuracy of the CK and the CK-SMG as well as the CKFG and CKFG-SMG models are compared, and the influence of the SMG assumption is inferred. The errors induced by each model are compared in a sensitivity study involving the plume thickness and the atmospheric path length as parameters. This study is conducted in two remote-sensing situations with different absolute pressures at sea level (105Pa) and at high altitude (16.6km, 104Pa). The comparisons are done on the basis of the error obtained for the integrated intensity while leaving a line of sight that is computed in three common spectral bands: 2000–2500cm−1, 3450–3850cm−1, and 3850–4150cm−1. In most situations, the SMG assumption induces negligible differences. Furthermore, compared to the CKFG model, the CKFG-SMG model results in a reduction of the computational time by a factor of 2.

scholarly journals Woody species do not differ in dormancy progression: differences in time to budbreak due to forcing and cold hardiness

2021 ◽  
Author(s):  
Al Kovaleski
Keyword(s):  
Maximum Rate ◽  
Path Length ◽  
Cold Hardiness ◽  
Woody Species ◽  
Two Dimensions ◽  
Spring Phenology ◽  
Wide Range ◽  
The Difference ◽  
Response To Temperature ◽  
Phenological Phases

AbstractBudbreak is one of the most observed and studied phenological phases in perennial plants. Two dimensions of exposure to temperature are generally used to model budbreak: accumulation of time spent at low temperatures (chilling); and accumulation of heat units (forcing). These two effects have a well-established negative correlation: the more chilling, the less forcing required for budbreak. Furthermore, temperate plant species are assumed to vary in amount of chilling required to complete endodormancy and begin the transition to breaking bud. Still, prediction of budbreak remains a challenge. The present work demonstrates across a wide range of species how bud cold hardiness must be accounted for to study dormancy and accurately predict time to budbreak. Cold hardiness defines the path length to budbreak, meaning the difference between the cold hardiness buds attain during the winter, and the cold hardiness at which deacclimated buds are predicted to open. This distance varies among species and throughout winter within a species. Increases in rate of cold hardiness loss (deacclimation) measured throughout winter show that chilling controls deacclimation potential – the proportion of the maximum rate response attained at high chill accumulation – which has a sigmoid relationship to chilling accumulation. For forcing, rates of deacclimation increase non-linearly in response to temperature. Comparisons of deacclimation potential show a dormancy progresses similarly for all species. This observation suggests that comparisons of physiologic and genetic control of dormancy requires an understanding of cold hardiness dynamics and the necessity for an update of the framework for studying dormancy and its effects on spring phenology.

Matrix form of interval multivariable gray model and its application

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sandang Guo ◽  
Yaqian Jing ◽  
Bingjun Li
Keyword(s):  
Three Dimensional ◽  
Original Data ◽  
Upper Bounds ◽  
Matrix Form ◽  
Gray Model ◽  
Interval Numbers ◽  
Content Type ◽  
The Matrix ◽  
Number Sequences ◽  
The Difference

PurposeThe purpose of this paper is to make multivariable gray model to be available for the application on interval gray number sequences directly, the matrix form of interval multivariable gray model (IMGM(1,m,k) model) is constructed to simulate and forecast original interval gray number sequences in this paper.Design/methodology/approachFirstly, the interval gray number is regarded as a three-dimensional column vector, and the parameters of multivariable gray model are expressed in matrix form. Based on the dynamic gray action and optimized background value, the interval multivariable gray model is constructed. Finally, two examples and comparisons are carried out to verify the effectiveness of IMGM(1,m,k) model.FindingsThe model is applied to simulate and predict expert value, foreign direct investment, automobile sales and steel output, respectively. The results show that the proposed model has better simulation and prediction performance than another two models.Practical implicationsDue to the uncertainty information and continuous changing of reality, the interval gray numbers are used to characterize full information of original data. And the IMGM(1,m,k) model not only considers the characteristics of parameters changing with time but also takes into account information on lower, middle and upper bounds of interval gray numbers simultaneously to make better suitable for practical application.Originality/valueThe main contribution of this paper is to propose a new interval multivariable gray model, which considers the interaction between the lower, middle and upper bounds of interval numbers and need not to transform interval gray number sequences into real sequences. According to combining different characteristics of each bound of interval gray numbers, the matrix form of interval multivariable gray model is established to simulate and forecast interval gray numbers. In addition, the model introduces dynamic gray action to reflect the changes of parameters over time. Instead of white equation of classic MGM(1,m), the difference equation is directly used to solve the simulated and predicted values.

Polarization of Separating Invariants

2008 ◽  
Vol 60 (3) ◽  
pp. 556-571 ◽  
Author(s):  
Jan Draisma ◽  
Gregor Kemper ◽  
David Wehlau
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Group Actions ◽  
Upper Bounds ◽  
Weyl’S Theorem ◽  
Finite Group Actions ◽  
Separating Invariants ◽  
The Difference ◽  
Special Case

AbstractWe prove a characteristic free version of Weyl’s theorem on polarization. Our result is an exact analogue ofWeyl’s theorem, the difference being that our statement is about separating invariants rather than generating invariants. For the special case of finite group actions we introduce the concept of cheap polarization, and show that it is enough to take cheap polarizations of invariants of just one copy of a representation to obtain separating vector invariants for any number of copies. This leads to upper bounds on the number and degrees of separating vector invariants of finite groups.

scholarly journals VLBI observations of the G25.65+1.05 water maser superburst

2019 ◽  
Vol 491 (3) ◽  
pp. 4069-4075 ◽  
Author(s):  
R A Burns ◽  
G Orosz ◽  
O Bayandina ◽  
G Surcis ◽  
M Olech ◽  
...  
Keyword(s):  
Path Length ◽  
Massive Star ◽  
Very Long Baseline Interferometry ◽  
Complex Structure ◽  
Rapid Onset ◽  
Line Of Sight ◽  
Star Forming ◽  
Long Baseline ◽  
Vlbi Observations ◽  
Water Maser

ABSTRACT This paper reports observations of a 22 GHz water maser ‘superburst’ in the G25.65+1.05 massive star-forming region, conducted in response to an alert from the Maser Monitoring Organisation (M2O). Very long baseline interferometry (VLBI) observations using the European VLBI Network (EVN) recorded a maser flux density of 1.2 × 104 Jy. The superburst was investipgated in the spectral, structural, and temporal domains and its cause was determined to be an increase in maser path length generated by the superposition of multiple maser emitting regions aligning in the line of sight to the observer. This conclusion was based on the location of the bursting maser in the context of the star-forming region, its complex structure, and its rapid onset and decay.

On the optimal control of cancer radiotherapy for non-homogeneous cell populations

1993 ◽  
Vol 25 (01) ◽  
pp. 1-23 ◽  
Author(s):  
L. G. Hanin ◽  
S. T. Rachev ◽  
A. Yu. Yakovlev
Keyword(s):  
Cellular Response ◽  
Optimization Problems ◽  
Complete Solution ◽  
Upper Bounds ◽  
Approximation Procedure ◽  
Probability Metrics ◽  
New Family ◽  
Homogeneous Cell ◽  
The Difference ◽  
Extremal Values

Optimization problems in cancer radiation therapy are considered, with the efficiency functional defined as the difference between expected survival probabilities for normal and neoplastic tissues. Precise upper bounds of the efficiency functional over natural classes of cellular response functions are found. The ‘Lipschitz' upper bound gives rise to a new family of probability metrics. In the framework of the ‘m hit-one target' model of irradiated cell survival the problem of optimal fractionation of the given total dose into n fractions is treated. For m = 1, n arbitrary, and n = 1, 2, m arbitrary, complete solution is obtained. In other cases an approximation procedure is constructed. Stability of extremal values and upper bounds of the efficiency functional with respect to perturbation of radiosensitivity distributions for normal and tumor tissues is demonstrated.

Dimer coverings on the Tower of Hanoi graph

2019 ◽  
Vol 33 (07) ◽  
pp. 1950043
Author(s):  
Wei-Bang Li ◽  
Shu-Chiuan Chang
Keyword(s):  
Diatomic Molecules ◽  
Upper Bounds ◽  
Lower And Upper Bounds ◽  
Tower Of Hanoi ◽  
N Stage ◽  
Dimension 2 ◽  
The Difference

We present the number of dimer coverings Nd(n) on the Tower of Hanoi graph THd(n) at n stage with dimension 2 [Formula: see text][Formula: see text]d[Formula: see text][Formula: see text] 5. When the number of vertices v(n) is even, Nd(n) gives the number of close-packed dimers; when the number of vertices is odd, it is impossible to have a close-packed configurations and one of the outmost vertices is allowed to be unoccupied. We define the entropy of absorption of diatomic molecules per vertex as S[Formula: see text][Formula: see text]=[Formula: see text][Formula: see text] Nd(n)/v(n), that can be shown exactly for TH2, while its lower and upper bounds can be derived in terms of the results at a certain n for THd(n) with 3 [Formula: see text][Formula: see text]d[Formula: see text][Formula: see text] 5. We find that the difference between the lower and upper bounds converges rapidly to zero as n increases, such that the value of S[Formula: see text] with d[Formula: see text]=[Formula: see text]3 and 5 can be calculated with at least 100 correct digits.

Freezing of Cells: Role of Ice and Solutes in Cell Damage

2007 ◽  
Author(s):  
Hiroshi Takamatsu
Keyword(s):  
Mechanical Stress ◽  
Cell Damage ◽  
Cellular Damage ◽  
Elevated Concentration ◽  
Cellular Injury ◽  
Extracellular Solution ◽  
Different Types ◽  
A Cell ◽  
The Difference

The mechanism of cellular damage associated with freezing of biological cells is discussed by summarizing the author’s recent studies that consists of four different types of experiments. The “solution effects” that designate the influence of elevated concentration of electrolytes during freezing is examined first by a nonfreezing experiment that exposes cells to hypertonic solutions using a perfusion microscope. The cell damage due to the solution effect is evaluated directly from a pseudo-freezing experiment, where cells were subjected to the milieu that simulated a freeze-thaw process in the absence of ice. Contribution of ice formed in the extracellular solution is then estimated from the difference in cell survival between the pseudo-freezing experiment and a corresponding freezing experiment. The cellular injury by the mechanical stress is also examined independently by a cell deformation experiment, which mimicked the situation that cells are compressed and deformed between ice crystals. This experiment was designed to examine a complex effect of mechanical stress from ice and elevated concentration of electrolytes. Based on all these experiments, the role of concentrated solutes and ice is revealed as a function of freezing conditions.

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